Waveguide and optical motion sensor using optical power modulation

Abstract

An optical motion sensing device included a sensor frame defining an opening, a sensor pad disposed in the opening, an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, and an output unit. The optical sensing system includes an optical waveguide, an optical source device, and an optical detector. The optical waveguide is positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide. The optical source device supplies optical energy to the optical waveguide. The optical detector detects an amount of optical energy exiting the optical waveguide. The output unit is configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal.

1. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide, and 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; 
 a load spring attached to at least a portion of the sensor frame and also supporting the sensor pad, and configured to counter at least some of a pressure exerted against the sensor pad, and further adapted to allow a desirable displacement of the sensor pad at a maximum pressure; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     2. The optical motion sensing device of  claim 1 , wherein the load spring is adapted to provide a maximum displacement of the sensor pad between 0.5 and 3 millimeters at a maximum pressure. 
   
   
     3. The optical motion sensing device of  claim 1 , wherein the optical waveguide comprises a siloxane elastomer. 
   
   
     4. The optical motion sensing device of  claim 1 , wherein the optical waveguide comprises an elastomer selected from the group consisting of polysiloxane, polyurethane, polybutadine rubber, and combinations thereof. 
   
   
     5. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising; 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, the optical waveguide comprising a numerical aperture of between 0.2 and 0.4, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     6. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, the optical waveguide comprising a core and a cladding, the core having a refractive index between 1.43 and 1.50, the cladding having a refractive index between 1.39 and 1.48, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     7. The optical motion sensing device of  claim 6 , wherein the core, the cladding, or both the core and the cladding have a Shore A hardness of between 25 and 75. 
   
   
     8. The optical motion sensing device of  claim 1 , further comprising a waveguide support structure comprising a non-compliant surface, the waveguide support supporting at least a portion of the optical waveguide. 
   
   
     9. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide, and 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; 
 a waveguide support structure comprising a non-compliant surface, the waveguide support supporting at least a portion of the optical waveguide, wherein the optical sensing system is further adapted for the movement of the sensor pad to cause a flexural deformation in an unsupported portion of the optical waveguide in response to an arterial pulse; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     10. The optical motion sensing device of  claim 1 , further comprising a flexible and incompressible support surface that supports the optical waveguide over substantially all of its length. 
   
   
     11. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide, and 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; 
 a flexible and incompressible support surface that supports the optical waveguide over substantially all of its length, wherein the waveguide support surface is a flexible electronic circuit board, to which the waveguide is bonded with a flexible elastomer adhesive; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     12. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide, and 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; 
 a flexible and incompressible support surface that supports the optical waveguide over substantially all of its length, wherein the optical source device and the optical detector are mounted on the surface of the waveguide support; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     13. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide, and 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; 
 a flexible and incompressible support surface that supports the optical waveguide over substantially all of its length; 
 a support return element which is configured within the support surface for the optical waveguide and adapted to oppose the flexing of the support surface; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal. 
 
   
   
     14. The optical motion sensing device of  claim 13 , wherein the support return element is adapted to provide an increasing contact pressure between the sensor pad and the optical waveguide as the sensor pad moves from a rest position to a position of maximum displacement, with the optical waveguide adapted such that said increasing contact pressure causes a decreasing amount of light exiting the second end of the optical waveguide. 
   
   
     15. An optical motion sensing device comprising:
 a sensor frame defining an opening; 
 a sensor pad disposed in the opening; 
 an optical sensing system adapted to detect an amount of movement of the sensor pad in the sensor frame, the optical sensing system comprising: 
 (a) an optical waveguide positioned within the sensor frame such that the movement of the sensor pad results in the flexing or compressing of the optical waveguide, 
 (b) an optical source device to supply optical energy to a first end of the optical waveguide, and 
 (c) an optical detector to detect an amount of optical energy exiting a second end of the optical waveguide; and 
 an output unit configured to receive a signal indicative of the amount of optical energy exiting the optical waveguide and to generate a measure of the amount of movement of the sensor pad from the received signal, wherein the compression and flexing of the optical waveguide when the sensor pad is at the position of maximum contact pressure causes a reduction of 20-80% in the total amount of light exiting the optical waveguide. 
 
   
   
     16. The optical motion sensing device of  claim 15 , wherein the compression and flexing of the optical waveguide at the position of maximum contact pressure causes a reduction of 50-70% in the total amount of light exiting the optical waveguide. 
   
   
     17. The optical motion sensing device of  claim 1 , wherein the optical detector is optically coupled to optical waveguide such that the optical detector receives substantially of the optical energy from the optical source that does not escape from the sides of the sides of the optical waveguide. 
   
   
     18. A compliant waveguide for detecting arterial pulses comprising:
 a cladding having a flat surface and defining a lumen, the cladding comprising an elastomer having a Shore A hardness of between 25 and 75; and 
 a core disposed in the lumen, the core comprising an elastomer having a Shore A hardness of between 25 and 75 and a refractive index greater than the refractive index of the cladding. 
 
   
   
     19. The compliant waveguide of  claim 18 , wherein the optical waveguide comprises an elastomer selected from the group consisting of polysiloxane, polyurethane, polybutadine rubber, and combinations thereof. 
   
   
     20. The compliant waveguide of  claim 18 , wherein the cladding has a Shore A durometer of between 45 and 55 and the core has a Shore A hardness between 30 and 45. 
   
   
     21. The compliant waveguide of  claim 18 , wherein the waveguide is capable of guiding at least 10,000 modes. 
   
   
     22. The compliant waveguide of  claim 21 , wherein the waveguide is capable of guiding at least 50,000 modes. 
   
   
     23. The compliant waveguide of  claim 21 , wherein the core has a refractive index between 1.43 and 1.50 and the cladding has a refractive index between 1.39 and 1.48. 
   
   
     24. The compliant waveguide of  claim 18 , wherein the core has a radius of at least 45 micrometers. 
   
   
     25. The compliant waveguide of  claim 18 ,
 wherein the core comprises an elastomer selected from the group consisting of polysiloxane, polyurethane, polybutadine rubber, and combinations thereof, has a Shore A hardness between 30 and 45, has a refractive index between 1.45 and 1.47, and has a radius of between 150 and 200 micrometers; 
 wherein the cladding has a Shore A durometer of between 45 and 55 and has a refractive index between 1.39 and 1.41; and 
 wherein the waveguide has an NA of between 0.35 and 0.4.